Em Mon, Aug 08, 2022 at 03:52:38PM -0700, Andrii Nakryiko escreveu: > On Mon, Aug 8, 2022 at 3:52 PM Andrii Nakryiko > <andrii.nakryiko@xxxxxxxxx> wrote: > > > > On Sun, Aug 7, 2022 at 10:53 AM Yonghong Song <yhs@xxxxxx> wrote: > > > > > > Currently, the pahole treats 'char' or 'signed char' type > > > as unsigned in BTF generation. The following is an example, > > > $ cat t.c > > > signed char a; > > > char b; > > > $ clang -O2 -g -c t.c > > > $ pahole -JV t.o > > > ... > > > [1] INT signed char size=1 nr_bits=8 encoding=(none) > > > [2] INT char size=1 nr_bits=8 encoding=(none) > > > In the above encoding '(none)' implies unsigned type. > > > > > > But if the same program is compiled with bpf target, > > > $ clang -target bpf -O2 -g -c t.c > > > $ bpftool btf dump file t.o > > > [1] INT 'signed char' size=1 bits_offset=0 nr_bits=8 encoding=SIGNED > > > [2] VAR 'a' type_id=1, linkage=global > > > [3] INT 'char' size=1 bits_offset=0 nr_bits=8 encoding=SIGNED > > > [4] VAR 'b' type_id=3, linkage=global > > > [5] DATASEC '.bss' size=0 vlen=2 > > > type_id=2 offset=0 size=1 (VAR 'a') > > > type_id=4 offset=0 size=1 (VAR 'b') > > > the 'char' and 'signed char' are encoded as SIGNED integers. > > > > > > Encode 'char' and 'signed char' as SIGNED should be a right to > > > do and it will be consistent with bpf implementation. > > > > > > With this patch, > > > $ pahole -JV t.o > > > ... > > > [1] INT signed char size=1 nr_bits=8 encoding=SIGNED > > > [2] INT char size=1 nr_bits=8 encoding=SIGNED > > > > > > Signed-off-by: Yonghong Song <yhs@xxxxxx> > > > --- > > > > LGTM. > > Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx> Thanks, tested before/after, applied. Pushing out next for CI testing. - Arnaldo
